La Tabla Periódica. Periodic Table 3º E.S.O

Hello everyone,
As I explained in today's lesson, you have to watch a video of the evolution of the Periodic Table and answer to the following questions:

1.What did scientist look for in order to classify the elements?

2.How many elements are there in a triad according to Döbereiner?

3.Why he decided to classify the elements in triads?

4.Why Döbereiner system was a failure?

5.How many elements have been discovered by the time Newlands decided to order them?

6.Which criteria Newlands used to classify the elements?

7.How many elements had Newlands’ octaves?

8.Newlands could not classify all the known elements, how many of them could not be classified?

9.Which property Mendeleiev used to classify the elements in his table?

10.Why did he leave empty spaces in the table?

11.What is a period? What is a group?

12.Noble gases were found before Mendeleiev studies: true or false?

13.Why hydrogen was very difficult to classify?

14.Is manganese (Mn) similar to halogens (F,Cl, Br,I)?

15.Which property Moseley chose to order the elements?

Good luck!